Deblended and deghosted seismic data

ABSTRACT

Deblending and deghosting seismic data may include processing blended seismic data acquired after actuation of a first seismic source located at a first depth and a second seismic source located at a second depth. The processing may comprise deblending and deghosting the blended seismic data based on a difference in ghost responses of the first seismic source and the second seismic source.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Divisional of U.S. National Stage application Ser.No. 15/326,806, filed Jan. 17, 2017 and published as U.S. PublicationNo. 2017-0276817 A1 on Sep. 28, 2017, which is a § 371 of InternationalApplication No. PCT/EP2015/080501, filed on Dec. 18, 2015 and publishedas WO 2016/097295 on Jun. 23, 2016, which claims the benefit of U.S.Provisional Application 62/093,600, filed Dec. 18, 2014, which isincorporated by reference in its entirety.

BACKGROUND

In the past few decades, the petroleum industry has invested heavily inthe development of marine survey techniques that yield knowledge ofsubterranean formations beneath a body of water in order to find andextract valuable mineral resources, such as oil. High-resolution imagesof a subterranean formation are helpful for quantitative interpretationand improved reservoir monitoring. For a typical marine survey, a marinesurvey vessel tows one or more sources below the sea surface of thewater and over a subterranean formation to be surveyed for mineraldeposits. Receivers may be located on or near the seafloor, on one ormore cables towed by the same or another marine survey vessel, or on oneor more cables towed by another vessel. The marine survey vesseltypically contains marine survey equipment, such as navigation control,source control, receiver control, and recording equipment. The sourcecontrol may cause the one or more sources, which can be air guns, marinevibrators, electromagnetic sources, etc., to produce signals at selectedtimes. Each signal is essentially a wavefield that travels down throughthe water and into the subterranean formation. At each interface betweendifferent types of rock, a portion of the wavefield may be refracted,and another portion may be reflected, which may include some scattering,back toward the body of water to propagate toward the sea surface. Thereceivers thereby measure a wavefield that was initiated by theactuation of the source.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an elevation or xz-plane view of marine seismicsurveying in which acoustic signals are emitted by a seismic source forrecording by seismic receivers for processing and analysis in order tohelp characterize the structures and distributions of features andmaterials underlying the solid surface of the subterranean formation.

FIGS. 2A-2E illustrate data graphs associated with deblended anddeghosted seismic data.

FIGS. 3A-3E illustrate data graphs associated with deblended anddeghosted seismic data.

FIG. 4 illustrates a method flow diagram associated with deblended anddeghosted seismic data.

FIG. 5 illustrates a method flow diagram associated with deblended anddeghosted seismic data.

FIG. 6 illustrates a diagram of a system associated with deblended anddeghosted seismic data.

FIG. 7 illustrates a diagram of a machine associated with deblended anddeghosted seismic data.

DETAILED DESCRIPTION

The present disclosure is related to deblending and deghosting ofseismic data. For example, a number of seismic sources may be actuated,resulting in a number of ghosts, each ghost associated with a seismicsource. As used herein, associated means connected to, in communicationwith, related to, and/or corresponding to, though embodiments are not solimited. Seismic data, as used herein may include source and receiverwavefields and may be acquisition data. Seismic data collected as aresult of the actuations may be collected as blended data. That blendeddata may be processed, and the processing may include deblending anddeghosting the seismic data.

As used herein, ghosts are delayed reflections trailing a seismic sourceactuation. A ghost results from reflections from a sea surface. Ghostsmay interfere with primary reflections, limiting useable bandwidth andintegrity of seismic data. When associated with blended seismic data,they may be referred to as interfering blended seismic source responses(associated with the seismic source) or interfering blended seismicghost responses (associated with a ghost). Seismic data resolution maybe degraded by the presence of ghosts.

As used herein, deghosting is the removal of a ghost from seismic data.Deghosting, for instance, may be performed using a number of differentdeghosting algorithms. Deblending, as used herein, is the separation ofblended seismic data. For instance, seismic data may be collected frommultiple seismic source actuations. This seismic data and associatedghosts may be blended as is it collected. Blending may occur because ofoverlapping actuations or simultaneous actuations. Additionally,blending may occur because of overlapping or simultaneous collection ofseismic data. The seismic data and associated ghosts may be deblended,or separated, in some examples to make the data compatible withdeghosting algorithms. Deghosting algorithms may use single seismicsource and/or ghost inputs, and deblending seismic data and associatedghosts may allow for this.

As used herein, a “seismic source” refers to one or more single sourcedevices, arranged as a source element, source unit, or source array. Asource element is a single source device, such as an air gun or marinevibrator. A source unit is a plurality of source elements that areactuated together. A source array is a plurality of source elements or aplurality of source units that may be actuated separately.

While some other approaches to deblending and/or deghosting utilizedeblending by actuation repetition including the actuation of a seismicsource multiple times on a same location in a blended experiment,examples of the present disclosure include deblending and deghostingwithout a repeated actuation. Further, deblending and deghosting inaccordance with the present disclosure may include deblending anddeghosting seismic data received as a result of more than one actuation.Deblending and deghosting in accordance with the present disclosure maydeblend seismic data in a blended (or simultaneous seismic source)experiment, including the seismic sources ghosts. This may increasedeblending performance for data coming from blended acquisitions, suchas simultaneous long offset (SLO) and stacked configurations. As usedherein, SLO refers to utilizing dithered actuation times of simultaneousseismic sources for acquiring long seismic data offsets. A stackedconfiguration is a configuration including one seismic source aboveanother at a same location but different depths. In such configurations,the stacked seismic sources may be actuated at a certain time delay. Theincrease in deblending performance may lead to more advanced blendingacquisition designs.

It is to be understood the present disclosure is not limited toparticular devices or methods, which may, of course, vary. It is also tobe understood that the terminology used herein is for the purpose ofdescribing particular embodiments only, and is not intended to belimiting. As used herein, the singular forms “a”, “an”, and “the”include singular and plural referents unless the content clearlydictates otherwise. Furthermore, the words “can” and “may” are usedthroughout this application in a permissive sense (i.e., having thepotential to, being able to), not in a mandatory sense (i.e., must). Theterm “include,” and derivations thereof, mean “including, but notlimited to.” The term “coupled” means directly or indirectly connected.

The figures herein follow a numbering convention in which the firstdigit or digits correspond to the drawing figure number and theremaining digits identify an element or component in the drawing.Similar elements or components between different figures may beidentified by the use of similar digits. As will be appreciated,elements shown in the various embodiments herein may be added,exchanged, and/or eliminated so as to provide a number of additionalembodiments of the present disclosure. In addition, as will beappreciated, the proportion and the relative scale of the elementsprovided in the figures are intended to illustrate certain embodimentsof the present invention, and should not be taken in a limiting sense.

FIG. 1 illustrates an elevation or xz-plane 101 view of marine seismicsurveying in which acoustic signals are emitted by a seismic source fordetecting and/or recording by seismic receivers for processing andanalysis in order to help characterize the structures and distributionsof features and materials underlying the solid surface of thesubterranean formation. FIG. 1 shows a domain volume 102 comprising asolid volume 104 of sediment and rock below the solid surface 106 of thesubterranean formation that, in turn, underlies a fluid volume 108 ofwater having a free surface 109 such as in an ocean, an inlet or bay, ora large freshwater lake. The domain volume 102 shown in FIG. 1represents an example experimental domain for a class of marine seismicsurveys. FIG. 1 illustrates a first sediment layer 110, an uplifted rocklayer 112, second, underlying rock layer 114, and hydrocarbon-saturatedlayer 116.

FIG. 1 shows an example of a marine survey vessel 118 equipped to carryout marine seismic surveys. In particular, the marine survey vessel 118may tow one or more cables 120 (shown as one cable for ease ofillustration) generally located near or below the free surface 109. Inat least one embodiment, cable 120 is a seismic streamer. The cables 120may be long cables containing power and data-transmission lines to whichseismic receivers may be connected. In one type of marine seismicsurvey, each seismic receiver, such as the seismic receiver representedby the shaded disk 122 in FIG. 1, comprises a pair of seismic receiversincluding a sensor detecting particle motion, displacement velocity oracceleration, and a hydrophone that detects variations in pressure. Thecables 120 and the marine survey vessel 118 may include sophisticatedsensing electronics and data-processing facilities that allow seismicreceiver readings to be correlated with absolute positions on the freesurface and absolute three-dimensional (3D) positions with respect to a3D coordinate system. In FIG. 1, the seismic receivers along the cablesare shown to lie below the free surface 109, with the seismic receiverpositions correlated with overlying surface positions, such as a surfaceposition 124 correlated with the position of seismic receiver 122. Themarine survey vessel 118 may also tow one or more seismic sources 126that produce acoustic signals as the vessel 118 and towed cables 120move along the free surface 109. Seismic sources 126 and/or cables 120may also be towed by other vessels, or may be otherwise disposed influid volume 108. For example, seismic receivers may be located on oceanbottom cables or nodes fixed at or near the solid surface 106, andseismic sources 126 may also be disposed in a nearly-fixed or fixedconfiguration. Consequently, as used herein, “cable” should be read torefer equally to a towed receiver (a.k.a. sensor) cable as well as to anocean bottom receiver cable.

FIG. 1 shows an expanding, spherical acoustic signal, represented bysemicircles of increasing radius centered at the seismic source 126,such as semicircle 128, following an acoustic signal emitted by theseismic source 126. Although only one seismic source is illustrated inFIG. 1, one, two, or more seismic sources may be present. The acousticsignals are, in effect, shown in vertical plane cross section in FIG. 1.The outward and downward expanding acoustic signal may eventually reachthe solid surface 106, at which point the outward and downward expandingacoustic signals may partially reflect from the solid surface and maypartially refract downward into the solid volume, becoming elasticsignals within the solid volume. Cables 120 are located a particulardistance apart. This distance may be approximately consistent betweenall adjacent cables towed by a single vessel, some adjacent cables, orthe distance may be inconsistent among cables. As used herein,“approximately” may include a distance within a particular margin,range, and/or threshold.

Examples of the present disclosure utilize seismic source actuations andtheir ghosts, in contrast to other approaches that utilize seismicsource actuations and their repetitions (actuation repetition methods).Responses of a seismic source and its ghost may be seen as a form ofblending two seismic sources together. In such an example, there may benot only a time delay between the two seismic sources, but also aspatial effect. A wavefield extrapolation may take both the spatialeffect and the time delay into account such that the seismic sourceresponse and the ghost response may be summed after wavefieldextrapolation. In response to the summation, an iterative thresholdingscheme may estimate the deghosted/deblended seismic source response. Forinstance, actuation repetition may be replaced by the seismic source andits ghost.

FIGS. 2A-2E illustrate data graphs associated with deblended anddeghosted seismic data. FIG. 2A illustrates data graph 260 including twoseismic source responses and their ghost responses. The data in datagraph 260 includes “blended” data. Data graph 260 illustrates resultsfrom two seismic sources actuated at the same time, referred to hereinas a left seismic source and right seismic source. For instance, datagraph 260 includes left seismic source response 230-1 and its ghostresponse 232-1. Ghost response 232-1, in this example, may be a sourceghost. Data graph 260 also includes right seismic source response 234-1and its ghost response 236-1. The time between source response 230-1 andghost response 232-1 may differ from the time between source response234-1 and ghost response 236-1. This difference may be present becausethe left seismic source may be at a particular depth, for instance 25meters, while the right seismic source may be at a different particulardepth, for instance, 16 meters. In the example illustrated in FIG. 2A,both the left and the right seismic source actuations have reflected atreflectors located at 200 meters, 310 meters and 380 meters.

For further processing, the data in FIG. 2A may be deblended. This mayinclude estimating a deghosted version of the left seismic source, asillustrated in FIG. 2D and a deghosted version of the right seismicsource, as illustrated in FIG. 2E.

In contrast to examples of deblending and deghosting in accordance withthe present disclosure, other approaches to deghosting use data that isnot blended. In such approaches, seismic source responses and theirghost responses are combined into responses that appear to be comingfrom a seismic source at a zero meter depth without any ghost response.

The deblending of the data in FIG. 2A may include an iterative processthat makes use of the different ghost responses associated with theright and the left seismic sources.

FIG. 2B illustrates a data graph 265 including a strengthening of theseismic source responses 230-1. As used herein, a strengthened seismicsource response includes a clearer and sharper response with greaterfocus, as compared to an unstrengthened seismic source response. Datagraph 265 includes an illustration of a subtraction of the data in FIG.2A after a backward extrapolation of 25 meters (shifting responses indata graph 260 upward) from the data in FIG. 2A after a forwardextrapolation of 25 meters (shifting responses in data graph 260downward). As a result, a forward extrapolation response 230-1 may be atthe same location in data graph 265 as response 232-1 after backwardextrapolation. The subtraction (a response 232-1 ghost value may have anopposite sign as a response 230-1 seismic source value) may be seen as afirst portion of deghosting of the left seismic source.

FIG. 2C illustrates a data graph 267 including a strengthening of theright seismic source response 234-1. Also illustrated in FIGS. 2B and 2Care corresponding ghost responses 232-2, 236-2, 232-3 and 236-3. In theembodiment, response 230-2 is larger and clearer in data graph 265 ascompared response 230-1, while response 234-2 is less clear thanresponse 234-1 in data graph 260. In at least one embodiment, along withthe subtraction, an inversion scheme may be used to strengthenresponses.

FIGS. 2D and 2E illustrate data graphs 268 and 269, respectively,illustrating estimated deblended and deghosted seismic source responses.Response 238 is an estimated deblended and deghosted seismic sourceresponse associated with the left seismic source. Response 240 is anestimated deblended and deghosted seismic source response associatedwith the right seismic source. An inversion algorithm may be used toexploit the selective strengthening illustrated in FIGS. 2B and 2C toestimate individual deblended and deghosted seismic source responseslike those illustrated in FIGS. 2D and 2E. In other words, thestrengthened responses may be used to determine which seismic sourcesare generating energy and how much energy is generated at each seismicsource. In an iterative inversion scheme, the strengthening may be usedas the first steepest descend step. The iterative inversion scheme maytry to explain the measured data in terms of the left deghosted anddeblended source responses and the right deghosted and deblended sourceresponses. In each iteration, it may use the strengthening for thoseparts of the data that it has not yet explained.

FIGS. 3A-3E illustrate data graphs associated with deblended anddeghosted seismic data. FIG. 3A illustrates a blended stackedconfiguration data graph 342, with a first seismic source actuated at aparticular depth, 25 meters in this example. In the example, a secondseismic source is actuated at a particular depth, 16 meters in thisexample. Response 350-1 is associated with the first seismic source, andresponse 352-1 is associated with the second seismic source.

FIG. 3B illustrates a data graph 344 showing a strengthening of theresponses of the first seismic source. For instance, response 350-2 isclearer and larger than response 350-1 illustrated in data graph 342.Response 352-2 is less clear than response 352-1 illustrated in datagraph 342. By using wavefield extrapolations that consider a particulardepth, followed by a subtraction, the seismic source response 350-2associated with the first seismic source may be strengthened.

FIG. 3C illustrates a data graph 346 showing a strengthening of theresponses of the second seismic source. For instance, response 352-3 isclearer and larger than response 352-1 illustrated in data graph 342.Response 350-3 is less clear than response 350-1 illustrated in datagraph 342. By using wavefield extrapolations that consider a particulardepth, followed by a subtraction, the seismic source response 352-3associated with the second seismic source may be strengthened.

FIGS. 3D and 3E illustrate estimated deblended and deghosted seismicsource responses. Response 354 is an estimated deblended and deghostedseismic source response associated with the first seismic source (andresponse 350-1). Response 356 is an estimated deblended and deghostedseismic source response associated with the second seismic source (andresponse 352-1). An inversion algorithm may be used to exploit theselective strengthening illustrated in FIGS. 3B and 3C to estimateindividual deblended and deghosted seismic source responses like thoseillustrated in FIGS. 3D and 3E. In other words, the strengthenedresponses may be used to determine which seismic sources are generatingenergy and how much energy is generated at each seismic source. In aniterative inversion scheme, the strengthening may be used as the firststeepest descend step. The iterative inversion scheme may try to explainthe measured data in terms of the first deghosted and deblended sourceresponses and the second deghosted and deblended source responses. Ineach iteration, the strengthening for those parts of the data that ithas not yet explained may be used.

The data graphs of FIGS. 3A-3E illustrate that, during seismic dataprocessing, a seismic source and its ghost may be used to strengthenresponses as compared to a different seismic source and its ghost. In astack configuration, for instance when two seismic sources are stackedon top of each other (at different depths), the seismic sources may beused together to strengthen the responses of actual seismic sources (noeffect on the free surface). This may remove an assumption of thesurface being a perfect acoustic mirror.

FIG. 4 illustrates a method flow diagram 460 associated with deblendedand deghosted seismic data. In at least one embodiment, the method maybe performed using a machine. The machine may be a single machine suchas a computing device, multiple machines, and/or any combination in adistributed network. At 461, blended seismic data is received. Theblended seismic data may include a first set of seismic data received inresponse to actuation of a first seismic source located at a first depthand a second set of seismic data received in response to actuation of asecond seismic source stacked with the first seismic source and locatedat a second depth. In at least one embodiment, the first set of seismicdata and the second set of seismic data are received in response to anSLO acquisition. In another embodiment, the first set of seismic dataand the second set of seismic data are received in response tosimultaneous actuation of the first and the second seismic sources.

At 478 the blended seismic data is deblended, and at 480 the deblendedseismic data is deghosted. In at least one embodiment, the seismic datais deblended based on a difference in ghost responses of the firstseismic source and the second seismic source, and the deblended seismicdata is deghosted based on the difference in ghost responses. Forinstance, seismic source actuations and their ghosts may be used duringdeblending and deghosting, as opposed to only actuation repetition. Inat least one embodiment, seismic data is identified and blended beforereceiving the blended seismic data. As used herein, identifying theseismic data includes indicating or determining that seismic data ispresent. In at least one embodiment, two or more seismic sources and oneor more seismic sensors may be towed, for instance via a cable, througha body of water above a subterranean formation, and the seismic data maybe identified from the one or more seismic sensors. This data may thenbe processed. For instance, blended, deblended, and deghosted. In yetanother embodiment, a deblended and deghosted seismic source response isbased on the deblended and deghosted data.

In at least one embodiment, interfering seismic data is removed from theestimated seismic source response based on the deblended and deghostedseismic data, and the remaining seismic data is deghosted. As usedherein, the remaining seismic data is seismic data that was not removedfrom the estimated seismic source response. The blended seismic data mayinclude a plurality of sets of seismic data, each set within theplurality of sets received in response to actuation of an associatedseismic source located at a particular depth, wherein the particulardepth is different for each set within the plurality of sets.

FIG. 5 illustrates a method flow diagram 562 associated with deblendedand deghosted seismic data. At 563, seismic data acquired afteractuation of a first seismic source and a second seismic source may bedeblended and deghosted. In at least one embodiment, deblending anddeghosting the blended seismic data is based on difference in ghostresponses of the first seismic source and the second seismic source. Forinstance, a first seismic source response may have a corresponding firstghost response, and second seismic source response may have acorresponding second ghost response. The depth of the first and thesecond seismic sources may affect the first and the second seismicsource responses, as well as the corresponding ghost responses. Thedifferences in the ghost responses may be used in deblending anddeghosting.

In at least one embodiment, the deblending and deghosting may includestrengthening a first seismic source response associated with the firstseismic source, strengthening a second seismic source responseassociated with the second seismic source, and estimating a deblendedand deghosted seismic source response based on the strengthened firstand second seismic source responses.

In some examples, the blended seismic data may be deblended anddeghosted based on a non-flat air-water surface. In other examples, itmay be based on a not-fully-reflective air-water surface. For instance,an uneven sea surface, whether physically or reflectively uneven, may beconsidered during deblending and deghosting. In at least one example,the air-water surface may not act as a perfect acoustic mirror, soadjustments may be made, for instance in algorithms, to deghost withouterroneous assumptions. If not considered, estimates may be lessaccurate, as seismic source and ghost responses may vary based on thesea state and its reflectivity.

An interfering blended seismic ghost response and/or an interferingblended seismic source response may be removed from the estimateddeblended and deghosted seismic source response based on the deblendedand deghosted data. For instance, seismic data associated with the firstseismic source may be removed, and processing may be focused on seismicdata associated with the second seismic source (and vice versa). In anexample, removing interfering seismic data associated with the secondseismic source may allow for an estimate for the first seismic source, acreation of an associated ghost, and deghosting of seismic dataassociated with the first seismic source, but not the second seismicsource.

In a number of examples, blended seismic data acquired after actuationof a first seismic source at a first time and a second seismic source ata second time may be deblended and deghosted. The first and the secondtime, as used herein, are different times. Alternatively oradditionally, blended seismic data acquired after simultaneous actuationof the first seismic source at a first depth and the second seismicsource at a second depth may be deblended and deghosted. As used herein,simultaneous actuation occurs when the first seismic source and thesecond seismic source are actuated at approximately the same time.

FIG. 6 illustrates a diagram of a system 670 associated with deblendedand deghosted seismic data. The system 670 may include a data source672, a subsystem 674, and/or a number of engines such as acquisitionengine 676 and may be in communication with the data source 672 (or datastore) via a communication link. The system 670 may include additionalor fewer engines than illustrated to perform the various functionsdescribed herein. The system may represent program instructions and/orhardware of a machine, for instance machine 784 as referenced in FIG. 7.As used herein, an “engine” may include program instructions and/orhardware, but at least includes hardware. Hardware is a physicalcomponent of a machine that enables it to perform a function. Examplesof hardware may include a processing resource, a memory resource, alogic gate, etc.

The number of engines may include a combination of hardware and programinstructions that is configured to perform a number of functionsdescribed herein. The program instructions, such as software, firmware,etc., may be stored in a memory resource such as a machine-readablemedium, computer-readable medium, etc., as well as hard-wired programsuch as logic. Hard-wired program instructions may be considered as bothprogram instructions and hardware.

The processing engine 676 may include a combination of hardware andprogram instructions configured to process blended seismic data acquiredafter actuation of a first seismic source located at a first depth and asecond seismic source located at a second depth. Processing engine mayinclude a combination of hardware and program instructions configured todeblend and deghost the blended seismic data based on a difference inghost response of the first seismic source and the second seismicsource. The blended seismic data may include a first seismic sourceresponse, a first ghost response associated with the first seismicsource response, a second seismic source response, and a second ghostresponse associated with the second seismic source response. While twoseismic sources are described herein, more or fewer seismic sources,associated ghosts, and associated responses may be used.

In at least one embodiment, the processing engine 676 may include acombination of hardware and program instructions configured to processthe blended seismic data acquired after actuation at a first time of thefirst seismic source and actuation at a second time of the secondseismic source. This blended seismic data may be processed, and the timedifferences may be used in deblending and deghosting including indeblending and deghosting algorithms.

In yet another embodiment, the processing engine 676, may include acombination of hardware and program instructions configured to processthe blended seismic data acquired after iterative actuation of the firstseismic source as a first time and actuation of the second seismicsource at varying times. As used herein, iterative actuation isactuation performed in a repetitive manner. Put another way, seismicsources are repeatedly actuated. The iterations may occur atpredetermined or random intervals. As used herein, varying times includenon-patterned times.

The processing may include deblending and deghosting the blended seismicdata based on a difference in ghost responses of the first seismicsource and the second seismic source. The difference in ghost responsesmay be based on a difference between the first depth and the seconddepth. For instance, a first seismic source response may have acorresponding first ghost response, and second seismic source responsemay have a corresponding second ghost response. The depth of the firstand the second seismic sources may affect the first and the secondseismic source responses, as well as the corresponding ghost responses.The differences in the ghost responses may be used in deblending anddeghosting. For instance, in deblending and deghosting algorithms.

In some examples of the present disclosure, the processed blendedseismic data may be acquired after simultaneous actuation of the firstseismic source and the second seismic source. In such an example, thefirst seismic source and the second seismic source may be in a stackedconfiguration.

The processed blended seismic data, in some instance, may be iterativelyacquired. For example, the first seismic source may be iterativelyactuated at a first time, and the second seismic source may beiteratively actuated at varying times. Such an example allows for aconstant actuation time for the first seismic source and randomactuation times for the second seismic source. Iterative actuations mayalso allow for an accurate deblended and deghosted seismic sourceresponse estimation.

FIG. 7 illustrates a diagram of a machine 784 associated with deblendedand deghosted seismic data. The machine 784 may utilize software,hardware, firmware, and/or logic to perform a number of functions. Themachine 784 may be a combination of hardware and program instructionsconfigured to perform a number of functions and/or actions. Thehardware, for example, may include a number of processing resources 786and a number of memory resources 788, such as a machine-readable mediumor other memory resources 788. The memory resources 788 may be internaland/or external to the machine 784, for example, the machine 784 mayinclude internal memory resources and have access to external memoryresources. The program instructions, such as machine-readableinstructions, may include instructions stored on the machine-readablemedium to implement a particular function, for example, an action suchas reconstructing a wavefield. The set of machine-readable instructionsmay be executable by one or more of the processing resources 786. Thememory resources 788 may be coupled to the machine 784 in a wired and/orwireless manner. For example, the memory resources 788 may be aninternal memory, a portable memory, a portable disk, and/or a memoryassociated with another resource, for example, enabling machine-readableinstructions to be transferred and/or executed across a network such asthe Internet. As used herein, a “module” may include programinstructions and/or hardware, but at least includes programinstructions.

Memory resources 788 may be non-transitory and may include volatileand/or non-volatile memory. Volatile memory may include memory thatdepends upon power to store information, such as various types ofdynamic random access memory among others. Non-volatile memory mayinclude memory that does not depend upon power to store information.Examples of non-volatile memory may include solid state media such asflash memory, electrically erasable programmable read-only memory, phasechange random access memory, magnetic memory, optical memory, and/or asolid state drive, etc., as well as other types of non-transitorymachine-readable media.

The processing resources 786 may be coupled to the memory resources 788via a communication path 790. The communication path 790 may be local orremote to the machine 784. Examples of a local communication path 790may include an electronic bus internal to a machine, where the memoryresources 788 are in communication with the processing resources 786 viathe electronic bus. Examples of such electronic buses may includeIndustry Standard Architecture, Peripheral Component Interconnect,Advanced Technology Attachment, Small Computer System Interface,Universal Serial Bus, among other types of electronic buses and variantsthereof. The communication path 790 may be such that the memoryresources 788 are remote from the processing resources 786, such as in anetwork connection between the memory resources 788 and the processingresources 786. That is, the communication path 790 may be a networkconnection. Examples of such a network connection may include a localarea network, wide area network, personal area network, and theInternet, among others.

As shown in FIG. 7, the machine-readable instructions stored in thememory resources 788 may be segmented into a number of modules 792 thatwhen executed by the processing resources 786 may perform a number offunctions. One module is illustrated in FIG. 7, but more modules may bepresent. As used herein, a module includes a set of instructionsincluded to perform a particular task or action. The number of modulesmay be sub-modules of other modules. For example, the processing module792 may be a sub-module of a deblending and/or a deghosting module (notillustrated) and/or process module 792 and/or the deblending anddeghosting modules may be contained within a single module. Thedeblending and deghosting modules may include instructions executable todeblend and deghost blended seismic data acquired after actuation of afirst seismic source and a second seismic source. Furthermore, thenumber of modules may comprise individual modules separate and distinctfrom one another. Examples are not limited to the specific module 792illustrated in FIG. 7.

Each of the number of modules may include program instructions and/or acombination of hardware and program instructions that, when executed bya processing resource 786, may function as a corresponding engine asdescribed with respect to FIG. 6. For example, the processing module 792may include program instructions and/or a combination of hardware andprogram instructions that, when executed by a processing resource 786,may function as the processing engine 676.

In accordance with a number of embodiments of the present disclosure, ageophysical data product may be produced. Geophysical data may beobtained and stored on a non-transitory, tangible machine-readablemedium. In at least one embodiment, obtaining the geophysical dataproduct includes towing two or more seismic sources and one or moreseismic sensors, for instance on a cable, through a body of water abovea subterranean formation and obtaining the geophysical data from the oneor more seismic sensors. The two or more seismic sources may be towed inline with one after another.

The geophysical data product may be produced by processing thegeophysical data offshore or onshore either within the United States orin another country. If the geophysical data product is produced offshoreor in another country, it may be imported onshore to a facility in theUnited States. The geophysical data product may be recorded on anon-transitory machine-readable medium suitable for importing onshore.

In some instances, once onshore in the United States, geophysicalanalysis may be performed on the geophysical data product. In someinstances, geophysical analysis may be performed on the geophysical dataproduct offshore. For example, blended seismic data acquired afteractuation of a first seismic source located at a first depth and asecond seismic source located at a second depth may be processed. Theprocessing may comprise deblending and deghosting the blended seismicdata based on a difference in ghost responses of the first seismicsource and the second seismic source.

Although specific embodiments have been described above, theseembodiments are not intended to limit the scope of the presentdisclosure, even where only a single embodiment is described withrespect to a particular feature. Examples of features provided in thedisclosure are intended to be illustrative rather than restrictiveunless stated otherwise. The above description is intended to cover suchalternatives, modifications, and equivalents as would be apparent to aperson skilled in the art having the benefit of this disclosure.

The scope of the present disclosure includes any feature or combinationof features disclosed herein (either explicitly or implicitly), or anygeneralization thereof, whether or not it mitigates any or all of theproblems addressed herein. Various advantages of the present disclosurehave been described herein, but embodiments may provide some, all, ornone of such advantages, or may provide other advantages.

1. A method, comprising: deblending and deghosting blended seismic dataacquired after actuation of a first seismic source and a second seismicsource, comprising: strengthening a first seismic source responseassociated with the first seismic source; strengthening a second seismicsource response associated with the second seismic source; andestimating a deblended and deghosted seismic source response based onthe strengthened first and the strengthened second seismic sourceresponses.
 2. The method of claim 1, further comprising deblending anddeghosting the blended seismic data based on a difference in ghostresponses of the first seismic source and the second seismic source. 3.The method of claim 1, further comprising deblending and deghosting theblended seismic data based on at least one of a non-flat and anot-fully-reflective air-water surface.
 4. The method of claim 1,further comprising removing an interfering blended seismic ghostresponse from the estimated deblended and deghosted seismic sourceresponse based on the deblended and deghosted data.
 5. The method ofclaim 1, further comprising removing an interfering blended seismicsource response from the estimated deblended and deghosted seismicsource response based on the deblended and deghosted data.
 6. The methodof claim 1, further comprising deblending and deghosting blended seismicdata acquired after actuation, at a first time, of the first seismicsource and actuation, at a second time, of the second seismic source. 7.The method of claim 1, further comprising deblending and deghostingblended seismic data acquired after simultaneous actuation of the firstseismic source at a first depth and the second seismic source at asecond depth.
 8. A system, comprising: a data store; and a processinghardware engine configured to: deblend and deghost blended seismic dataacquired after actuation of a first seismic source and a second seismicsource; strengthen a first seismic source response associated with thefirst seismic source; strengthen a second seismic source responseassociated with the second seismic source; and estimate a deblended anddeghosted seismic source response based on the strengthened first andthe strengthened second seismic source responses.
 9. The system of claim8, wherein the processing hardware engine is configured to process theblended seismic data acquired after actuation at a first time of thefirst seismic source and actuation at a second time of the secondseismic source.
 10. The system of claim 8, wherein the processinghardware engine is configured to process the blended seismic dataacquired after iterative actuation of the first seismic source at afirst time and actuation of the second seismic source at varying times.11. The system of claim 8, wherein the blended seismic data comprises: afirst seismic source response; a first ghost response associated withthe first seismic source response; a second seismic source response; anda second ghost response associated with the second seismic sourceresponse.
 12. The system of claim 8, wherein the processing hardwareengine is configured to strengthen the first and the second seismicsources based on a difference in ghost responses of the first seismicsource and the second seismic source resulting from a depth differencebetween the first and the second seismic sources.
 13. A method,comprising: receiving blended seismic data, the blended seismic dataincluding: a first set of seismic data received in response to actuationof a first seismic source located at a first depth; and a second set ofseismic data received in response to actuation of a second seismicsource stacked with the first seismic source and located at a seconddepth; and deblending and deghosting blended seismic data acquired afteractuation of a first seismic source and a second seismic source,comprising: strengthening a first seismic source response associatedwith the first seismic source; and strengthening a second seismic sourceresponse associated with the second seismic source.
 14. The method ofclaim 13, wherein deblending the blended seismic data comprisesstrengthening the first response and the second response using wavefieldextrapolation.
 15. The method of claim 13, further comprising estimatinga deblended and deghosted seismic source response based on the deblendedand deghosted seismic data.
 16. The method of claim 15, furthercomprising: removing interfering seismic data from the estimated seismicsource response based on the deblended and deghosted seismic data; anddeghosting remaining seismic data.
 17. The method of claim 13, whereinthe first set of seismic data and the second set of seismic data areacquired in response to simultaneous actuation of the first and thesecond seismic sources.
 18. The method of claim 13, wherein the blendedseismic data includes a plurality of sets of seismic data, each setwithin the plurality of sets acquired in response to actuation of anassociated seismic source located at a particular depth, wherein theparticular depth is different for each set within the plurality of sets.19. The method of claim 13, wherein the first set of seismic data andthe second set of seismic data are acquired in response to asimultaneous long offset (SLO) acquisition.
 20. The method of claim 13,further comprising: towing two or more seismic sources and a pluralityof seismic sensors through a body of water above a subterraneanformation; and identifying the seismic data from the plurality ofseismic sensors.